For a long as retired zoologist John Darby can remember there has not been a successful breeding pair of crested grebes on Lake Hāwea. But now there is!

The pair have laid two eggs.

“I have been aware that grebes have attempted to breed here in the past.  But they have always failed because of the conditions that prevail on the lake,” Darby said.

“This would be the first to breed successfully if they do so.”

They have a very complex lifecycle, Darby said.

“They can barely walk on land which is a big problem and so as an escape mechanism they build a floating nest, usually under willow trees. The reason for that is that they brood their chicks on their back, not underneath them. Within an hour of the chicks hatching they will climb onto the back of the adult. It is an anti-predator strategy. It is the only bird I know that can physically remove its chicks from danger.”

If the lake levels rise the nests become detached and float away, and if the lake levels go down the nest is exposed to predation, Darby said.

“This is why floating nesting platforms have been designed for the grebe population on Lake Wānaka, and we have installed one on Lake Hāwea for this pair.”

The birds showed far more interest in the nesting platform when we presented them with it than the nest they were building and within hours were improving on it, he said.

Darby doesn’t recognize the pair. He said he was unable to “mark” the grebes in Wānaka with a leg band because 99 per cent of the time their legs are underwater.

If one egg hatches and the bird has a chick on its back, it will generally cut its losses and desert any other eggs that might be in the nest, said Darby. So it is crucial to know when the eggs are laid to calculate when they will hatch, usually 24 days later. It is not uncommon for eggs to be laid two days apart. The hatching period can span as long as a week, depending on how many eggs there are.

Both the male and female share in the incubation of the eggs. And share in feeding the chicks.

“The reaction of the Hawea people has been wonderful; they are very determined the birds will get everything that they need,” Darby said.

Read edition 1002 of the Wānaka Sun here.